can any of you astronomytards maybe help dig up like, a 3d model of how the moon orbits the earth? or one with the earth/moon in relation to the sun as well, demonstrating how the shadow on the moon is cast (or the bright side lit up if that's the case?) i can only find like, flat 2D ones that show it as being totally planar. surely if there is so much variation it can't be totally planar, right? like does it go around in a wobble or a cloud (like a diagram of electrons around a nucleus in an atom)
sorry if this sounds retarded, like i said, trying to imagine how it works in 3d space boggles my noggin
Quoting: Anonymous Coward 1595910 I will try to explain this.
How the moon looks is depending on a lot of factors:
1. Position of the observer, date and time
2. Field rotation
3. Orbital time of the Moon around Earth
4. Orbital eccentricity of the Moon
5. Inclination of the moons orbit
6. Orbital eccentricity of the Earth
7. Inclination of Erath axis
All this movement is quite complex and an observer on Earth will see the Moon in exact the same position only after 18.something years.
But the most significant and noticable change is the field rotation.
Let's take a Moon in it's 3rd quarter, a waning, halflit Moon.
It rises around midnight and sets around noon.
Let's now go to the equator around the time of the summer or winter solstice.
(Actually you have to be a little offside of the equator because of the inclined (tilted) moon orbit, but let us make it simple)
Go out at midnight and face east to see the Moon rise.
You will notice, that the terminator (the border between the lit and dark side) is horizontal - lit site down, dark side up.
(Most people who are the first time close to the equator are a little surprised to see it like this)
You watch it rising as Earth rotates around its axis - 1 o'clock, 2, 3 - you have to lean back as its going higher in the sky - still lit site down, dark side up.
4 o'clock, 5, 6 - it's now direct overhead, quite uncomfortable to watch, but still lit site down, dark side up.
7 o'clock, 8 - if you go on watching the Moon (now in the daylight) and don't care, you fall on your ass - but still lit site down, dark side up.
You can now make a headstand to keep on watching - but most probably you will turn to the west.
But what's that? Now the lit side is up and the dark side is down.
You turn back to the east and bow back and again lit site down, dark side up.
Facing east: lit site down, dark side up - facing west: lit side is up and dark side down.
Obviously it is not the Moon that turns around, it is you.
Now lets go back in time - to the rising Moon at midnight.
But now we move away from the equator to the north by let's say 25° (to the south in the southern hemispere).
When the moon rises you will notice, that the terminator is no more horizontal - it's tilted by the amount you went to the north (south).
When you follow the path of the Moon from low in the east, now high in the south (north) and low in the west, you turn around and earth rotates.
Apparently the moon rotates - at moon rise the terminator is tilted to the right (left), at its highest point it's vertical and when the Moon sets its tilted to the left (right).
But it is you and the Earth that turn around and rotate. It's the same phenomenon as it is at the equator.
Of course this is an ideal set of parameters - the terminator is not vertical most times of the year - because we didn't take into accont the above mentioned numbers 3 to 7.
But for the times around the solstices it's quite accurate.
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